Conventionally, surgical instruments have been made of metal. In this case there is no problem in sterilizing the instruments using an autoclave where they are heated up 135.degree. C. The application of plastics for surgical instruments, however, has some advantages over metal: it can easily be molded in complicated shapes, it has a light weight, and it is less expensive than metal. Especially for elaborate instruments, such as those used in minimally invasive surgery or in laparoscopic operations, there is a trend to manufacture from plastics.
In many cases, the whole instrument or part of the instrument is designed to be disposable after the operation. To save costs it is often advantageous if the instrument has some reusable parts, which have to sterilized in an autoclave after the operation. Some plastic materials can resist heightened temperatures during this process (120.degree. C. to 135.degree. C.), for instance, polyetherimide. Generally, even these plastic instruments by autoclave only for a limited number of times (on the order of 10 times), because they age, crack, etc. Consequently the instruments are less reliable after having been heated too often.